1. Field of the Invention
This invention relates to the connectorization of flat cable and, in particular, to such a cable of the type having two overlying/underlying arrays of conductors isolated by a common insulative center film, with each array being laminated between opposite sides of the center film and a different one of two insulated outer films.
2. Background of the Invention
In one particular type of flat cable designed for telephone under carpet cable applications, known as TUCC* flat cable (*registered trademark of the Western Electric Company), two precisely offset arrays of overlying/underlying conductors are separated by an insulative center film, with each array being adhesivey bonded directly to only the respectively adjacent one of two mutually disposed insulative outer films. The conductors are preferably of rectangular or ribbon configuration so as to allow a given flat cable to be fabricated with minimum thickness. This becomes of paramount importance when such cables must be folded back upon themselves, such as when used in certain under-carpet wiring applications. One preferred form of such a multi-arrayed cable is disclosed in a co-pending application of W. A. Elliott-T. J. Taylor, Ser. No. 106,599, filed Dec. 26, 1979, and assigned to the same assignee as the present invention.
Flat cables of the type in question have generally been connected to conventional solder type connectors, in particular, heretofore, by first stripping the insulation from short, terminated end regions of the conductors, and then positioning them in, and soldering them to, respectively aligned U-shaped solder cups or receptacles of the connector. As disclosed in a co-pending application of T. J. Taylor, Ser. No. 116,704, filed Jan. 30, 1980, also assigned to the same assignee as the present invention, it has proven advantageous to angularly twist such terminated stripped ends of the conductors a predetermined number of degrees, preferably in the range of 45 to 90 degrees from their original (horizontal) orientation as confined within the cable, prior to being nested within and soldered to the respectively associated connector receptacles. Such twisted conductor ends have been found to substantially improve soldered connection reliability, and facilitate lateral conductor displacement whenever required for alignment with the receptacles of a given connector.
Regardless whether the conductor ends of a flat cable of the type of primary concern herein are angularly twisted or not prior to their soldered connectorization, they normally must be completely stripped of insulation, which is a time consuming and relatively expensive operation.
There have also been a number of other techniques employed heretofore for terminating and connectorizing flat cables of various other types. For example, in S. K. Tally U.S. Pat. No. 2,973,502, two flat cables, each comprised of one or more ribbon conductors secured to only one side of a suitable plastic film, are laminated together such that the respectively aligned conductors in the two cables are brought into mating relationship. The composite cable is terminated by initially separating and thereafter folding an end section of each cable, including the one or more conductors bonded thereto, back upon itself in accordance with one illustrative embodiment. The resulting folded-back and exposed conductor ends may then be inserted into a female-type connector to effect cable conductor-connector contact engagement. Because of the as-fabricated mating relationship of the paired conductors within the composite cable, the overlying/underlying conductors cannot be separately accessed. As such, the composite cable, in actuality, functions as a flat cable with only a single array of laterally disposed conductors. Indeed, it is because of the mating contact between the respectively aligned overlying/underlying pairs of conductors that the terminated end of such a composite laminated cable may be subsequently re-divided into two cable end sections so as to effect the folded-back exposure of the commonly connected pairs of conductors for connectorization.
Another variation of a terminated and connectorized flat cable is disclosed in L. P. Weisenburger U.S. Pat. No. 3,772,776. In one embodiment of that patent, the terminating ends of an array of conductors, laminated between two insulative films, are stripped of insulation on only one side thereof. The terminated end of the cable is then folded back into an open U-shaped configuration, and thereafter inserted within a space defined between a substrate and an array of outwardly extending tunnel wires of a memory plane. Upon the exposed conductors being brought into respective engagement with the tunnel wires, soldered connections are completed therebetween. Thus, in establishing such soldered connections, it is seen that the insulation must first be removed from one side of the terminated, single array of cable conductors. Such an insulation stripping operation, as previously noted, can add appreciably to the costs involved in connectorizing a flat cable, even when only a single array of conductors are involved.
IBM Technical Disclosure Bulletin, Vol. 5, No. 11, April 1963, pages 22-23, discloses a technique for interconnecting two cables, each having a single array of conductors, wherein the insulation is first removed on only one side of each cable along a terminated end region thereof, with the partially stripped end regions of the two cables then being bent 90 degrees and brought into mating relationship within a receiving slot formed in a spring-biased, C-shaped clamping member. This technique for interconnecting two flat cables likewise cannot be employed to independently connectorize the conductors of a multi-arrayed cable, whether constructed in the manner of primary concern herein, or constructed as separate cables which are bonded or otherwise secured together to form a composite cable.